Today conventional pH-measurement in industrial processes including water-conditioning and waste-control, is usually performed with a glass electrode combined with a reference electrode and sometimes a thermometric sensor, in a so-called combination electrode or electrode system. This system is then electrically connected through conduits and junction boxes to an amplifier system with read-out and/or recording and controlling functions, in a separate location more easily accessible to controlling personnel. For the measurements thus obtained to be meaningful, the electrode system has to be checked and maintained on a frequent schedule, most times daily, sometimes weekly. Due to the technology of these electrode systems, this maintenance has to be performed carefully by specially trained technicians -- a cost factor of pH-control which can be higher than the initial cost of the system itself over the life span of the electrode system, short as that life span may be. Even more disconcerting is the fact that the technology applied in today's electrode systems may lead to sudden, unpredictable breakdown of its pH-reporting function even with a frequent maintenance schedule. Since such breakdown unforeseeably interrupts process control the result will be losses for the manufacturer or, in waste control, pollution problems for the community.
It has therefore, been the object of this invention to reduce the frequency of scheduled maintenance and to virtually eliminate the known sources of unpredictable breakdown. Instead, the electrode system may be expected to work for an extended period without causing losses, until finally gradual symptoms of aging will lead to replacement at one of the scheduled checkups.